84099991 has 2 divisors, whose sum is σ = 84099992. Its totient is φ = 84099990.

The previous prime is 84099989. The next prime is 84100007. The reversal of 84099991 is 19999048.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 84099991 - 2¹ = 84099989 is a prime.

Together with 84099989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (84099791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42049995 + 42049996.

It is an arithmetic number, because the mean of its divisors is an integer number (42049996).

Almost surely, 2^84099991 is an apocalyptic number.

84099991 is a deficient number, since it is larger than the sum of its proper divisors (1).

84099991 is an equidigital number, since it uses as much as digits as its factorization.

84099991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 209952, while the sum is 49.

The square root of 84099991 is about 9170.6047237900. The cubic root of 84099991 is about 438.1256198832.

It can be divided in two parts, 8409999 and 1, that added together give a square (8410000 = 2900²).

The spelling of 84099991 in words is "eighty-four million, ninety-nine thousand, nine hundred ninety-one".